This invention relates to microphone shields, and more particularly to shielding a microphone from environmental effects.
High-quality reproduction of sound using available sound recording techniques and equipment is desirable in variety of applications. For example, high-quality, low-noise sound reproductions are important in television and movie industry, radio communication, and wireless telephone devices. Clean voice and dialog reproduction may be desired in the presence of ambient and background noise levels of moderate to high amplitude.
One frequently encountered source of undesirable background noise is caused by air or liquid moving relative to a sound-transducing device, such as a microphone. This type of noise may occur due to environmental conditions. For example, wind may cause distortion of the microphone-sensing membrane. Rain may also cause impact noise as drops of rain land on the microphone. Further, the combination of wind and rain may degrade the structure of the microphone with heat and moisture.
There are several prior art designs that have used open cell foam or cloth, known as a xe2x80x9cwind sockxe2x80x9d in the recording industry, to reduce the effect of wind noise on microphones. For example, in some embodiments, Drever (U.S. Pat. No. 4,600,077) and McCormick (U.S. Pat. No. 5,808,243). use xe2x80x9cwind sockxe2x80x9d designs that provide alternate layers of foam 102 and air spaces 104 to improve the microphone 100 performance (see FIG. 1). However, these techniques are often ineffective in wind conditions above approximately 10 kph.
Electronic filtering techniques have also been used to filter out wind noise. However, electronic filtering also attenuates desired audio frequencies, thereby substantially degrading sound quality.
In recognition of the above-described problems with the prior designs, the inventors have developed a system that enables relatively low-noise microphone sensing in wind speeds of up to 80 kph, and in some cases, even beyond 80 kph. The inventors recognized that high wind conditions, above a wind speed threshold of about 10 kph, cause pressure imbalances between the front and rear sides of the microphone-sensing element.
The present invention includes a microphone shield system including an impervious elastic membrane stretched over and covering a microphone on at least one side. The impervious elastic membrane is adapted to pass a selected acoustical frequency range. The selected acoustical frequency range excludes a frequency range of noise from environmental effects, such as wind and rain.
The system also includes an opening to allow a plurality of wires to pass through the impervious-elastic membrane. The plurality of wires provides connections to the microphone.
The present invention also includes a method for shielding a microphone from noise created by environmental effects, such as wind and rain. The method includes stretching an impervious elastic membrane over the microphone to form an enclosure, and passing a plurality of wires through the impervious elastic membrane to provide connections to the microphone.
The present invention further includes a wireless telephone device. The device includes housing and communication electronics within the housing. The communication electronics provides transmission and reception of electronic signals. The device also includes a microphone and an impervious elastic membrane stretched over and covering the microphone on at least one side. The impervious elastic membrane is adapted to pass a selected acoustical frequency range, where the selected acoustical frequency range excludes a frequency range of noise from environmental effects, such as wind and rain.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.